In order to use a medical instrument in image-guided surgery, the instrument has to be calibrated, verified and/or validated, i.e., the dimensions, configuration and/or arrangement of the instrument are made known to a navigation system or the like. Otherwise, for example, if the instrument is damaged (e.g., bent), healthy tissue that lies next to tissue to be treated may be impinged by the instrument.
A device and method for calibrating a bent element are known from EP 1 413 258 A1, wherein the bent element is connected to a navigation element, placed onto a calibrating device, and moved while resting on said calibrating device until the element is calibrated.
The navigational calibration of medical instruments or implants is known from EP 1 369 090 A1. A spatial position of the instrument or implant is ascertained by means of a medical navigation system. This enables the relative position of the instrument or implant to be ascertained with respect to anatomical data, wherein the spatial orientation of a multi-dimensionally configured, functional section of the instrument or implant can be ascertained.
U.S. Pat. No. 6,428,547 B1 describes detecting the shape of a treatment device, wherein the treatment device is referenced in a computer-controlled, camera-assisted navigation system by means of a marker array attached to the treatment device. Projections of the treatment device can be detected by means of radiographic images, and, in the navigation system, the shape of the treatment device can be assigned to the projections via the position of the marker array in/on the projections.
A verification method for positions in camera images is known from U.S. Pat. No. 6,724,922 B1.
DE 199 44 516 A1 describes a method for detecting a shape of an object, wherein a camera image of the object is produced and an outline of the object is detected in a first plane by an evaluation unit (which is connected to the camera). The focusing distance of the camera is changed and an outline of the object is detected in a second plane by the evaluation unit. These steps are repeated until a sufficient number of outlines have been detected, such that the spatial shape of the object can be determined.
EP 1 667 067 A1 discloses a method for calibrating an instrument or implant to which at least one marker is attached. The position of the instrument or implant in space can be determined using the at least one marker. Outlines, a view and/or a geometry of the instrument or implant can be optically captured from at least one side and compared with corresponding outlines, views and/or geometries of stored pre-calibration data of the instrument or implant. A determination then can be made whether or not the instrument or implant is calibrated. A device for calibrating an instrument or implant includes a computational unit connected to a memory in which pre-calibration data of the instrument are stored; at least one camera, using which markers attached to the instrument can be captured; and at least one video camera, wherein the at least one camera and the video camera are connected to the computational unit and exhibit a defined positional relationship to each other. The positional relationship can be determined by the computational unit, and the image data of the instrument as captured by the video camera can be evaluated using the instrument position information as captured by the camera, such that said data can be compared with the pre-calibration data.
A system for determining the spatial position of a body is known from WO 99/17133 and WO 99/30182.